Aves, p�le ornithologique de Natagora

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Aves, 26/2 | 1989 | 73-87

  The Common Crossbill (Laxia curvirostra) in the North-East of the Belgian Ardennes from July 1983 to December 1987.
Schmitz, L.

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Article summary

A census of Common Crossbills, conducted in the Hertogen between A983 and 1987, showed invasional movements of variable intensity in four years of the five. The breeding population is correlated with the spruce fruiting, which also influences the timing of breeding. In the absence of srpuce seeds, larchs are exploited by the few remaning crossbills. The reproductive cycle does not have a strict annual periodicity : among the releasers, besides the availability of spruce seeds, the previous "history" of the bird seems siginificant. Autumn and winter breeders were more numerous at the end of 1987, when the population was mostly composed of adults that had not bred since 1986. The song is used in two separate contexts : reproduction and periods of high numbers, when the social context could be the stimulant. When the seed crop reaches a minimum at the end of the summer, Crossbills tend to withdraw to higher altitudes (more than 500-530 m).

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